Various types of substrate processing apparatuses are employed in semiconductor production to execute specific types of processing on target substrates undergoing the processing (hereafter may be simply referred to as “substrates”), such as semiconductor wafers and FPD (flat-panel display) substrates. For instance, a plasma processing apparatus is utilized to execute etching, film formation processing or the like with plasma generated over a substrate placed on a stage inside a processing chamber by raising a process gas supplied into the processing chamber to plasma as high-frequency power is applied to an electrode disposed inside the processing chamber.
Various parameters are set in such a processing apparatus so as to control or monitor its operating conditions. Various types of processing are executed in the processing apparatus under optimal conditions by controlling or monitoring the parameters. Such parameters include control data used to control the processing chamber internal temperature, the electrode temperature, the processing chamber internal pressure and the process gas flow rate, optical data used to ascertain the plasma state and electrical data provided from a matcher that matches the impedance at the electrode with the impedance at the high-frequency power source. During the substrate processing, the substrate processing apparatus is controlled by monitoring the individual parameters with corresponding measuring instruments so as to assure that the optimal processing is executed at all times.
Patent reference Japanese Laid Open Patent Publication No. H11-87323 (literature 1) and Japanese Laid Open Patent Publication No. 2004-39952 (literature 2) listed below disclose technologies whereby a plurality of process parameters are analyzed, any changes in the process characteristics or the system characteristics are detected by statistically correlating these parameters as analysis data and the analysis data are corrected based upon the extent to which the detection value fluctuates. There is also a method disclosed in the related art through which the plurality of parameters are compiled into several types of statistical data to be used as analysis data by adopting the method of principal component analysis, which is a type of multivariate analysis method, and the operating conditions of the processing apparatus are monitored and evaluated based upon the statistical data.
A substrate processing apparatus such as that described above may assume any of various apparatus states during substrate processing. For instance, the substrate processing apparatus engaged in continuous processing through which a plurality of substrates are continuously processed in a batch, may assume a substrate processing execution state during which the plurality of substrates are being continuously processed or an idling state waiting for the start of the continuous processing to be executed on the next batch of substrates after the completion of the continuous processing on the preceding batch. The other states that may be assumed in the substrate processing apparatus include a startup state following the apparatus assembly, a replacement-imminent state, in which a part in the substrate processing apparatus needs to be replaced soon, and an error state in which an abnormality has occurred in the apparatus.
As many as several tens of types of parameters are set and thus, the volume of the parameter data provided by the measuring instruments in the substrate processing apparatus is very large. Another factor resulting in the very large data volume in the related art is that since the parameter data corresponding to the various parameters are collected from the individual measuring instruments over fixed sampling cycles (e.g., 0.1 sec) regardless of the specific state the apparatus is currently in. A problem thus arises in that the storage capacity of the data storage means (e.g., a hard disk) where these data are saved becomes quickly depleted.
In addition, the data that must be analyzed in the event of an error in the substrate processing apparatus are mainly those collected while executing substrate processing. The presence of a large volume of data having been collected while the substrate processing apparatus was not engaged in the substrate processing, e.g., while the substrate processing apparatus was in the idling state, saved in the data storage means, leads to another concern that the data needed for the error analysis cannot be retrieved quickly. Furthermore, since no substrate is actually processed while the substrate processing apparatus is in the idling state, it is not necessary to collect a large volume of data in the idling state as long as no error has occurred in the substrate processing apparatus.
The storage capacity in the data storage means may be used more efficiently by lengthening the sampling cycle with which the data are obtained from the measuring instruments and thus reducing the volume of sampled data. However, if the sampling cycle is shortened regardless of the apparatus state, the volume of data collected while, for instance, the substrate processing is in progress will also be reduced. When it becomes necessary to analyze such data, the data analysis accuracy may be compromised. There is another factor to be considered in that it is more desirable to use a data storage means with a smallest possible storage capacity so as to minimize the manufacturing cost.